Grape thrips

Drepanothrips reuteri

Thrips are small insects, 0.04 inch long, with distinctive feathery wings. Color varies from yellow to brown in color. Grape thrips and western flower thrips are the most important species causing damage on grapes. Both species may be found in most grape-growing areas. Grape thrips populationsusually reach their greatest numbers in July; this coincides with peak vine growth, and as vine growth slows, the numbers of thrips decreases. Western flower thrips populations peak in May, coinciding with grape bloom and the drying up of winter plant hosts.

Damage
Table grapes are susceptible to fruit damage caused by the western flower thrips. They create halo-spotting on the fruit when they oviposit in berries during bloom and up to fruit set or shortly thereafter. Both western flower thrips and grape thrips can scar berries with their feeding, which renders certain white varieties used for table grapes unmarketable. Thrips scarring is primarily a problem on Red Globe, Calmeria, Italia, and occasionally on Thompson Seedless. Fruit feeding discontinues in summer when both species feed on new vegetative growth.

In the North Coast, western flower thrips can feed in emerging shoots in early spring and stunt shoots and cause leaves to cup, especially during cool, rainy springs. Grape thrips may attack shoot tips in late spring or early summer although damage does not become apparent until the population has already decreased. While summer damage of leaves by thrips is common, it is not considered a problem for most varieties. However, a heavy grape thrips population can be a problem in Salvadors.

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